Rapping device that alternately impacts cathode sheets along the bottom edge during hydraulic stripping operations



Oct. 13, 1970 P. M. JASBERG 3 3,533,887

RAPPING DEVICE THAT ALTERNATELY IMPACTS CATHODE SHEETS ALONG. THE BOTTOM EDGE DURING HYDRAULIC STRIPPING OPERATIONS Filed Oct. 21, 1968 5 Sheets-Sheet 1 INVENTOR.

Oct. '13, 1970 Y P. M. JASBERG 3,533,887

RAPPING DEVICE THAT ALTERNATELY IMPACTS CATHODE SHEETS ALONG THE BOTTOM EDGE DURING HYDRAULIC STRIPPING OPERATIONS Filed Oct. 21, 1968 3 Sheets-Sheet 2 I IN\-"ENTOR.

Perm M. Jksbsk "2/544 fizz M flTTys.

Oct. 13, 1970 P. M. JASBERG 3,533,887

- RAPPING DEVICE THAT ALTERNATELY IMPACTS CATHODE SHEETS ALQNG THE BOTTOM EDGE DURING HYDRAULIC STRIPPING OPERATIONS Filed Oct. 21, 1968 INVENTOR.

PETER M. Jiasbsn q BY 3 Sheets-Sheet s United States Patent 3,533,887 RAPPING DEVICE THAT ALTERNATELY IMPACTS CATHODE SHEETS ALONG THE BOTTOM EDGE DURING HYDRAULIC STRIPPING OPERATIONS Peter M. Jasberg, Kellogg, Idaho, assignor to The Bunker Hill Company, a corporation of Delaware Filed Oct. 21, 1968, Ser. No. 769,254

Int. Cl. 332]) US. Cl. 156-584 5 Claims ABSTRACT OF THE DISCLOSURE A rapping device for stripping deposited metal layers from opposed planar surfaces of a cathode after electrolytic recovery of the metal. The rapping device comprises a yoke that straddles the bottom edge of the cathode. A pneumatic cylinder impacts the yoke against the two deposited metal surfaces in rapid succession to flex the cathode and disengage the deposited metal layers. The apparatus is used in cooperation with a hydraulic stripping apparatus to insure complete removal of the deposited layers from each cathode.

CROSS REFERENCES TO RELATED APPLICATIONS The general process of stripping electrolytically deposited layers of metal from cathodes, such as in a zinc recovery process, is discussed in detail in my co-pending application Ser. No. 636,797, filed May 8, 1967, titled Process for Stripping Metal from a Cathode now Pat. No. 3,501,385. A rather complete description of a production apparatus for carrying out such method is contained in my co-pending application Ser. No. 707,095 filed Feb. 21, 1968, titled Hydraulic Cathode Stripper for Metals Electrolytically Deposited now Pat. No. 3,472,249.

BACKGROUND OF THE INVENTION As described in the above mentioned patent applications, the hydraulic stripping of electrolytically deposited metals such as zinc greatly increases cathode life and reduces the incidence of cathode damage caused by conventional manual stripping procedures. However, under certain operating conditions, the complete removal of such metal layers is not insured when using hydraulic jets directed at the top of the deposited metal layers alone. To accomplish fully automated hydraulic stripping, one must insure that very few, if any, cathodes pass through the stripping apparatus without all deposited metal being removed from both surfaces thereof. To solve this recurring difficulty that was encountered in actual practice, the rapping or impacting device described herein was developed and utilized.

SUMMARY OF THE INVENTION The invention relates to an apparatus that includes an upwardly open U-shaped yoke that straddles the lower edge of the cathode and overlaps the surfaces of deposited metal thereon. The yoke is suitably supported for reciprocable movement in a straight line perpendicular to the metal surfaces. It is activated by a pneumatic cylinder that reciprocates the yoke against the metal surfaces in rapid reversing succession. The cathode itself is suspended along its upper end in a fashion that provides suificient yieldability to prevent plate failure due to the cyclic loading condition.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross sectional view through a typical stripping apparatus showing the mounting of the present rapping device;

3,533,887 Patented Oct. 13, 1970 DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 and 2, the apparatus that is the subject matter of this disclosure is shown in conjunction with a cathode assembly 10 as used in the electrolytic recovery of zinc. The particular cathode assembly 10 comprises a fiat sheet of aluminum, having an insulating layer 11 of suitable resin bonded to the sheet along its side edges and across its top surfaces. The metal layer that is deposited electrolytically upon the cathode assembly 10 is a rectangular sheet, designated by the numeral 12, bounded along its upper end by a solution line 13 where the layer 12 meets the layer of resin 11. The cathode is supported by an upper header bar 14. It is guided through the stripping apparatus by front and rear hangers 15, 16 suitably carried by wheels 17 which ride along a supporting track 18. The hangers 15, 16 are fixed to and moved by a powered chain 20.

For hydraulic stripping purposes, each cathode assembly 10 is moved across one or more hydraulic nozzles 21 mounted on the supporting framework and aimed angularly downward toward the solution line 13. In addition to the hydraulic nozzles 21, pneumatic nozzles might also be incorporated to balloon the layers of deposited metal apart from the cathode assembly after initial separation due to the hydraulic forces.

To insure that the layers of deposited metal are removed from the cathode assembly 10 in each instance, it has been found necessary to utilize mechanical impacting of the metal layers along their lower edges. The apparatus for rapping the cathodes is shown at the lower portions of FIGS. 1 and 2, it being mounted 'by the side walls 22 of the stripping apparatus and framework.

The rapping device comprises an upright U-shaped yoke 23 which straddles the lower edge of each cathode assembly 10 as the cathode assembly 10 passes across the device. Resilient blocks 24 are fixed to the yoke 23 in opposed relation to minimize mechanical damage to the cathode assemblies 10 due to impact forces. The area of each pad 24 is sufficiently large to insure distribution of a force from yoke 23 t0 cathode assembly 10 without mechanical deformation, a practical size relationship being shown in FIG. 2.

Yoke 23 is supported by a guide bearing 25 that reciprocably receives a guide bar 26 extending from one side of yoke 23. The opposite side of yoke 23 is fixed to the outer end of the piston rod of a pneumatic cylinder assembly 27. The cylinder assembly 27 is preferably one that is capable of rapid reversal and high amplitude impact. A conventional pneumatic tamper is quite suitable for such purposes. The cylinder assembly 27 is mounted on a supporting concrete post 28 by means of a strong metal mounting bracket 30 and two collars 31 having trunnion mounting pins 32 pivotally carried by bracket 30. The apparatus is therefore capable of maintaining proper alignment and movement of yoke 23 without mechanical binding.

It is necessary to accurately guide the upper ends of the cathode assemblies 10 to prevent undesirable swinging of the cathode assemblies, which might cause disengagement of them from the hangers 15, 16. To this end, longitudinal guides 33 are provided, including resilient pads 34 which limit sideward movement of header bars 14, but permit some resilient accommodation of such movement to prevent cathode damage.

In operation, the device is either used immediately following the application of hydraulic pressure .to the solution line at each side of the cathode assembly or is used simultaneously during such application. In any event, the rapping device is activated after initial loosening of the deposited metal layers from the cathode sheet. As shown in FIGS. 3, 4 the cylinder assembly 27 first causes yoke 23 to impact the cathode assembly 10 in one direction, which will flex the cathode sheet and cause the heavier and more rigid metal layer to disengage from the sheet surface as it assumes a concave configuration. The yoke 23 is immediately reversed and then impacts the opposite surface of the cathode assembly lit to free the remaining metal layer in substantially the same manner.

The impact of the yoke 23 causes any remaining areas of attachment of the metal layers to shear and then fall from the cathode assembly due to its weight. The U- shaped yoke 23 provides an alternate reverse impact on opposite sides of the cathode sheet, thereby imposing stress reversal through cyclic loading and insuring removal of both layers of metal.

Local deformation of the cathode sheet is prevented by utilizing pads 24 of sufiicient area and by maintaining the velocity of the yoke 23 at a level low enough to prevent such deformation. The shape of the cathode sheet relative to the direction of force application and the low point on each sheet at which force is applied to it produces the least inertia resistance of the sheet to the force. The rubber pads 24 prevent damage to the cathode sheet in the event that a sheet is rapped after the deposited metal has stripped free and fallen clear of the more vulnerable aluminum sheet. The yieldable guide assembly at the top of the sheet reduces the possibility of cathode plate failure caused by fatigue under the cyclic loading conditions.

The high pressure water jets from nozzles 21 act to strip the deposited metal layers from the cathode assembly from the top toward the bottom of each sheet. The stripping operation of the hydraulic jets and the rapper compliment one another and insure completion of the stripping operation. Any metal layer not completely stripped prior to entering the rapper will have the top portion of the metal layer stripped free or at least loosened from the cathode surfaces because of the high pressure water jet forces. The imposed loading of the rapper device produces maximum bending moment at the top of the cathode along the area of solution line 13. This moment, coupled with the prior loosening of the metal layers due to the water jets adequately stresses the interface between the metals to shear the remaining bond that exists.

The stripping of the layer generally progresses from the top toward the bottom. In addition, there is sufficient mass in the deposited layers, in the case of zinc deposited on an aluminum cathode, to further utilize the inertia of the metal layer in assisting the stripping. As the rapping force of yoke 23 initially moves the cathode the metal layer moves in the direction of the applied force. The sudden reversal of this force causes the lighter cathode to begin reversal of its direction of travel while the previously freed portion of the metal layer continues traveling in the initial direction. This force reversal has ,ssassv been found to definitely accelerate the rate of stripping of the layers.

If desired, additional high pressure Water jets (not shown) might be utilized at the rapping area or following the rapping area. Such jets would be designed to impinge on the cathode plate well below the solution line and further assist in final removal of the zinc.

Many modifications might be made in the actual structure illustrated. This was designed solely as an example of the form of the apparatus, which is set out in the following claims.

Having thus described my invention, I claim:

1. In an apparatus for stripping deposited metal layers from opposed planar surfaces of a cathode previously in an electrolytic solution and coated with deposited metal layers along areas bounded by upper solution lines;

suspension means for supporting the cathode above the solution line in a free depending condition;

an upwardly open U-shaped yoke straddling the lower edge of the cathode and overlapping each of the deposited metal layers;

and means operatively connected to said yoke for impacting the yoke against the deposited layers of metal in rapid succession.

2. The apparatus as set out in claim 1 wherein the apparatus is combined with high pressure hydraulic jets directed downwardly toward the upper interfaces of the cathode planar surfaces and the deposited layers of metal along the upper solution lines.

3. An apparatus as set out in claim 1 wherein the yoke 'further includes resilient pads mounted in corresponding positions at each side of the yoke and facing one another, the inner surfaces of such pads being spaced from one another by a distance greater than the thickness of the cathode and layers of metal deposited thereon.

4. The apparatus as set out in claim 1 wherein the last named means comprises a pneumatic cylinder.

5. The apparatus as set out in claim 1 further comprising:

a guide bar fixed to and extending outwardly from the yoke; guide bearing means for slidably receiving the guide bar; the opposite side of the yoke being fixed to the outer end of the piston rod in a pneumatic cylinder assembly; the pneumatic cylinder assembly and guide bearing suitably supported in coaxial alignment along an axis perpendicular to the normal planar positions of the cathode surfaces.

References Cited UNITED STATES PATENTS 2,055,963 9/1936 Boss 204l2 2,183,496 12/1939 Peters -84 3,401,446 9/1968 Obeda et al. l56344 SAMUEL FEINBERG, Primary Examiner US. Cl. X.R. 

